The Battle for Wesnoth is probably one of the all time great open source games. It's been around for a long time, it's well polished and now it's looking to get on Steam.
Dungeon Rushers is a game I tested for the developer a while ago when they posted it to reddit, so they sent along a key to check out properly now it's out for Linux.
We should see this coming by now. The Cossacks 3 release date has been announced and I have it confirmed personally that the Linux release is now delayed.
I've enjoyed a great many hours in RimWorld. It has charming visuals much like Prison Architect, but you're building a colony with a choice of different AI behind the scenes.
After some delay, the latest DLC and patch for XCOM 2 is now out for Linux. Shen’s Last Gift adds mech units to the mix, to better fight the insidious alien threat.
Defect is a very cool idea for a spaceship combat game. You keep building a new ship to take on new challenges and your crew keep stealing it so you have to face it in combat.
I feel bad for the Battlestation: Harbinger developer, as I think it's a pretty nice name but another developer has coined the "Battlestation" term so they have to change their name. They will also be doing a free update soon.
We've been kicking around some ideas about doing a livestream of one of Paradox's grand strategy games. There's a pretty big fan base among GOL readers, so it would be interesting to see how much interest there is and what people would want.